Severe service ball valves are utilized in a number of processes and under a variety of conditions, including extreme temperatures, high pressures, abrasive particles, acidic fluids, heavy solids buildup, critical safety applications, large pressure differentials, velocity control, noise control, etc. Severe service ball valves may be characterized as valves suitable for use under relatively high pressures, pressure drops and/or temperatures. Pressure and/or pressure differentials may exceed 0.7 MPa (100 psi), 7 MPa (1000 psi) or even 70 MPa (10,000 psi), and temperatures may exceed 100° C., 200° C. or even 500° C. Difficult process streams may be corrosive, may include abrasive particulates, may be prone to solidification unless maintained above a particular temperature, may be prone to solids buildup, and the like. Severe service ball valves are characterized by metal-to-metal sealing contact between the ball and the seats of the valve.
In various processes, severe service ball valves may be employed in redundant legs or pathways of a process for a configuration which allows for selectively isolating the two pathways to maintain a process flow (or isolation) via one pathway, while providing service or maintenance on the unused, isolated leg. Likewise, various pathways may be employed in a severe service process in which different process steps may be required depending on the characteristics of a particular stream. An arrangement that has been used to provide for multiple paths within a system is shown in FIG. 1, wherein a multiport manifold 1 is attached to two or more severe service ball valves 2 via an intermediate flanged connection. However, dead volume in flow paths leading up to and within such alternate legs may be problematic in severe service applications, e.g., solids may accumulate in non-flow areas and stresses due to thermal cycling may become extreme.